1. Field of the Invention
The present invention relates to a position control system for controlling a position of an object using a stepping motor as a driving source, and more particularly, to a position control system for controlling a stepping motor according to a closed loop position control system.
2. Description of the Prior Art
In recent years, there have been significant improvements in the performance of various types of information apparatus. Consequently, there is a demand for a position controlling system having a higher speed and a higher precision in the power supply of the magnetic disc apparatus, printer, and other types of devices.
Heretofore, as a power supply for these types of apparatus, a stepping motor has been widely used, and a system of open-loop control has generally been adopted. The open-loop control system has an advantage in the simplicity of a corresponding control circuit, but, on the other hand, due to the constant risk of pulling out of the stepping motor, it is difficult to run it at a high speed. Another point is that, in stopping for position setting, the system is vibrated centering on the stopping point, and time is required for setting. Further, there is a limit in the accuracy of the position setting. It is well known that there are various difficult problems as mentioned above in realizing a high speed, high precision position setting system.
In the conventional position control system using a stepping motor, there has been required a step of delicately adjusting the phases of the polyphase signals and the mechanical angle of the stepping motor at a certain basic position of the stepping motor. Thus, there has been a problem of significant lowering of the mass productivity of the position control system.